It depends on which Royal Enfield they were talking about. The original company went out of business back in 1970 with a few oddball models lasting until 1972. These were all British.
The bikes made under license in India are not considered Royal Endfields, rather India Enfields, or depending on symantics.. Enfield India.
To confuse things further, Floyd Clymer tried to ressurect the Indian Motorcycle company by selling redesigned Royal Enfields that were re badged as Indian Chiefs, and these bikes were known as Indian Enfields. This was in the 50's.
I'm somewhat of a Royal Enfield nut... I love Bullets, Connies, and Interceptors and have owned some of these in the past. Most of the confusing history can be found in Roy Bacon's book "Royal Enfield, the Post War Models".
If you didn't know... most postwar Royal Enfields were manufactured in a cave were the temperature was a constant, therefore much closer tolerances were obtainable. They also took great pains to balance the crankshaft on several models. Ride a 750 Triumph Bonneville on the Hiway and then switch to an Interceptor, you won't believe the difference in power and smoothness. Those old Interceptors could easily crack 120 mph.
There is a lot of inaccurate info in that article...
I'm sorry... I get carried away with this stuff... I'll go away now..